Medial meniscus tear has been proposed as a potential etiology of spontaneous osteonecrosis of the knee (SONK). Disruption of collagen fibers within the meniscus causes meniscal extrusion, which results in alteration in load distribution in the knee. A recent study has demonstrated high incidence of medial meniscus extrusion in the knee with SONK. Our purpose was to determine whether the extent of medial meniscus extrusion correlates with the severity of SONK in the medial femoral condyle.

Anteroposterior and lateral knee radiographs were taken with the patients standing. Limb alignment was expressed as the femorotibial angle (FTA) obtained from the anteroposterior radiograph. The stage of progression of SONK was determined according to the radiological classification system described by Koshino. After measurement of anteroposterior, mediolateral, and superoinferior dimensions of the hypointense T1 signal intensity lesion of MRI, its ellipsoid volume was calculated with the three dimensions. Meniscal pathology (degeneration, tear, and extrusion) were also evaluated by MRI.

Of the 18 knees with SONK, we found 5 knees at the radiological stage 2 lesions, 9 knees at the stage 3, and 4 knees at the stage 4. Whereas the ellipsoid volume of SONK lesion significantly increased with the stage progression, the volume was significantly greater at stage 4 than stage 2 or 3. All the 18 knees with SONK in the present study showed substantial extrusion (> 3mm) and degeneration of the medial meniscus. While medial meniscal extrusion increased with the stage progression, medial meniscus was significantly extruded at stage 3 or 4 compared with stage 2. A significant increase in FTA was found with the stage progression. FTA was significantly greater at stage 4 than stage 2 or 3. Multiple linear regression analysis revealed that medial meniscus extrusion and FTA were useful predictors of the volume of SONK lesion.

This study has clearly shown a significant correlation between the extent of medial meniscus extrusion and the stage and volume of SONK lesion. Degeneration and tears of the medial meniscus in combination with extrusion may result in loss of hoop stress distribution in the medial compartment, which could increase the load in the medial femoral condyle. In addition to meniscal pathology, knee alignment can influence load distribution in the medial compartment biomechanically. Multiple linear regression analysis indicates that an increase in FTA concomitant with a greater extrusion of medial meniscus could result in greater lesion and advanced radiological stage of SONK. Taken together, alteration in compressive force transmission through the medial compartment by meniscus extrusion and varus alignment could develop subchondral insufficiency fractures in the medial femoral condyle, which is considered to be one of the main contributing factors to SONK development.

There was high association of medial meniscus extrusion and FTA with the radiological stage and volume of SONK lesion. Increased loading in the medial femoral condyle with greater extrusion of medial meniscus and varus alignment may contribute to expansion and secondary osteoarthritic changes of SONK lesion.

Introduction: Recent studies suggested that trans-epicondylar axis (TEA) as the origin of collateral ligament was valuable axis for the parallel cut of the posterior condyle. An alternative landmark of the angle between the TEA and anterior trochlear line of the lateral and medial femoral condyles (trochleo-epicondylar angle) for determining the rotational positioning of the femoral component could be considered. We here report a simple radiographic view with a landmark of the anterior and posterior femoral condyle for determining the rotational alignment of the femoral component in TKA.

Subjects and methods: Our new radiograph presented an axial view of distal femur of a patient. The patient lay in the supine position and flexed the knee about 120 to 130 degrees. An x-ray beam was applied to the knee at the angle of 20 degrees to the ground surface. We measured the external rotational angle between posterior condylar (PC) line and clinical TEA that was condylar twist angle, and the internal rotational angle between the anterior trochlear line (AT line) and clinical TEA. This study involved 122 knees in 82 patients with osteoarthritis of the knee, an average age of 67.3 years. And we compared our measured angle with the angle from 3D reconstructed images with 3-dimensional helical CT system (n=35).

Results: The former angle was 5.7° ± 3.2° and the latter was −5.6° ± 2.9°. There was a variation by individual patients, the condylar twist angle was negative correlation with tibio-femoral angle. The internal rotation angle of the trochlear line and clinical TEA (trochleo-epicondylar angle) was 4.9°±2.1°. The tibio-femoral angle was positively correlated with the trochlear line angle. The trochlear line angle from 3D-CT was 5.4°±1.9°. The average of the difference between our view and the 3D-CT was 0.5°± 1.0°, R=0.87 with a Spearman’s rank test.

Discussion and conclusion: We improved the simple radiographic view in order to evaluate the TEA and PC line, and also the anterior trochlear line, for assessing the rotational alignment of the distal femur in total knee arthroplasty (TKA). We are able to measure and evaluate both angles and do double-checking the condylar twist angle and trochlear line angle. Our new radiographic technique is easy to measure the condylar twist angle, and the angle between AT line and clinical TEA (trochleo-epicondylar angle), simple and reliable, and may be an alternative method for the assessment of TEA of the femur in TKA as preoperative planning.

Introduction: Recent studies suggested that trans-epicondylar axis (TEA) as the origin of collateral ligament was valuable axis for the parallel cut of the posterior condyle. An alternative landmark of the angle between the TEA and anterior trochlear line of the lateral and medial femoral condyles (trochleo-epicondylar angle) for determining the rotational positioning of the femoral component could be considered. We here report a simple radiographic view with a landmark of the anterior and posterior femoral condyle for determining the rotational alignment of the femoral component in TKA.

Subjects and methods: Our new radiograph presented an axial view of distal femur of a patient. The patient lay in the supine position and flexed the knee about 120 to 130 degrees. An x-ray beam was applied to the knee at the angle of 20 degrees to the ground surface. We measured the external rotational angle between posterior condylar (PC) line and clinical TEA that was condylar twist angle, and the internal rotational angle between the anterior trochlear line (AT line) and clinical TEA. This study involved 122 knees in 82 patients with osteoarthritis of the knee, an average age of 67.3 years. And we compared our measured angle with the angle from 3D reconstructed images with 3-dimensional helical CT system (n=35).

Results: The former angle was 5.6° ± 2.8° and the latter was −5.7° ± 3.2°. There was a variation by individual patients, the condylar twist angle was negative correlation with tibio-femoral angle. The internal rotation angle of the trochlear line and clinical TEA (trochleo-epicondylar angle) was 4.9°±2.1°. The tibio-femoral angle was positively correlated with the trochlear line angle. The trochlear line angle from 3D-CT was 5.6°±2.0°. The average of the difference between our view and the 3D-CT was 0.5°± 1.0°, R=0.87 with a Spearman’s rank test.

Discussion and conclusion: We improved the simple radiographic view in order to evaluate the TEA and PC line, and also the anterior trochlear line, for assessing the rotational alignment of the distal femur in total knee arthroplasty (TKA). We are able to measure and evaluate both angles and do double-checking the condylar twist angle and trochlear line angle. Our new radiographic technique is easy to measure the condylar twist angle, and the angle between AT line and clinical TEA (trochleo-epicondylar angle), simple and reliable, and may be an alternative method for the assessment of TEA of the femur in TKA as preoperative planning.

We investigated clinical features and surgical outcomes for compressive cervical myelopathy in patients over 75 years of age.

Twenty-one patients who underwent surgical decompression for cervical myelopathy were reviewed. The average age at the time of operation was 78.0 years and the mean follow-up period was 5.7 years. Posterior decompression in 19 patients and anterior decompression in 2 patients were performed. Neurologic deficits before and after surgery were assessed using a scoring system by the Japanese Orthopaedic Association (JOA score). Radiological features were examined with radiographs and MRI. The clinical results were compared to those of 24 control patients who were less than 65 years of age at the time of surgery. The average age was 50.2 years and the mean follow-up period was 4.5 years.

In the aged patients, the preoperative mean JOA score was 6.2. Radiological examination revealed that the spinal cord was multisegmentally impinged. The postoperative maximum JOA score averaged 11.1, and the recovery rate was 45.4%. All patients became ambulatory and independent in fundamental daily activities following surgery. Maximum recovery was obtained from 1 to 3 years after the operation and function was maintained for at least 3 years. At the final follow up, the mean JOA score had been reduced to 9.5 and the recovery rate to 27.4%. Only the preoperative duration of symptoms correlated with the outcomes. The pre-operative JOA score in the control patients was 6.5. The postoperative maximum JOA score was 13.8 and the recovery rate was 69.4%. This was not significantly changed at the final follow-up.

Although postoperative recovery of function was significantly inferior to that of the control patients, surgical treatment appears to be beneficial, even in patients over 75 years of age, in improving neurological function and ability of activities in daily living.

Vertebroplasty is a radiologically guided therapeutic procedure that consists of percutaneous injection of surgical cement into unhealthy vertebra. Vertebroplasty originated from radiologists in Europe to stabilize malignant vertebral tumor by injecting PMMA cement (polymethyI methaerylate) percutaneously with a fluoroscopic guidance. With the achievement of an analgesic effect associated with vertebral reinforcement, Gangi (1996) and other radiologists (1998) extended the use of percutaneous injection of PMMA to the patients with spinal osteoporosis.

Since 1991, the authors have developed biomechanical augmentation of osteoporotic vertebral fractures by injecting self-hardening bioactive calcium phosphate paste, and reported in 1995 that the increased mechanical strength and osteoconductivity of the surrounding bone were achieved by the augmentation by bioactive calcium phosphate cement in the experimentally induced osteoporotic animals. In 1998, the authors reported clinical experiences of repair of osteoporotic vertebral fracture using transpedicular injection of calcium phosphate paste in 15 patients with fresh fracture or with vertebral pseudoarthrosis.

Various kinds of bone-substitutes including hydroxyapatite, calcium phosphate, carbonate and others have been currently utilized to stabilize the fractured osteoporotic vertebra. As the number of the patients with osteoporotic vertebral fracture is increasing with growing elderly population, the repairing of the spinal osteoporosis using biomaterials will be needed more and more. The current treatment and the future’s task will be discussed.